Processes for catalytic benzene synthesis



FOR CATALYTIC nanznua s n'rmsrs PROCESSES Otto Roelen and Holten, Custodi No Drawing. Original a Serial No. 132,595. tion November 1, Germany April 1,

pplication Divided and th 1941, Serial No. 41 1936 Walter Feisst, Oberhausen- Germany; vested in the Allen Property an March 23, 1937,

is applica- Claims. (Cl. 260-449-8) This invention relates to processes for reacting carbon monoxide and hydrogen, and more particularly to benzene synthesis in the presence oi catalysts deposited on earlier substances.

This invention is a division of U. S. Serial No. 132,595, filed March 23, 1937, which matured into a Patent No. 2,261,184.

It is an object of this invention to provide improved catalytic materials, and to utilize such improved catalytic materials in processes for reacting carbon monoxide and hydrogen.

It is another object of this invention to provide processes for regenerating these catalysts after they have suffered a material reduction in ac-. tivity.

Other objects, and the manner in which the same are attained, will appear from the following description.

In large scale benzene synthesis from carbon monoxide and hydrogen the catalysts employed are metals of the iron group (iron, cobalt, nickel) such as kleselguhr prepared according to the method of this invention give normal yields in the conversion of mixtures of carbon monoxide and hydrogen into liquid hydrocarbons at the low reaction temperature or 180-185 C. These catalysts can be regenerated by treatment with hydrogen in the synthesis furnace itself.

The carrier materials can be produced either artificially or by a suitable treatment of minerals whose active constituents have been precipitated Certain ditficulties have been production of such catalysts,

onto kieselguhr. experienced in the as the kiesel'guhr brought into contact with acidic and alkaline reagents gives off soluble constituents which have an extremely prejudicial action on the catalytic substance.

Thus for example when kieselguhr is added to the allraline precipitating solution for the metal catalysts, a part'oi' the sllicl'c acid of the kieselguhr dissolves in the form of alkali silicate, and reacts with the heavy-metal salts to form in soluble heavy-metal silicates which cannot be reduced to metal and thus prejudicially afifect the activity of the catalyst.

Therefore care should be taken that none of the disturbing constituents dissolve out from the carrier mass. This can be prevented when kieseluhr or powdered asbestos is used by reducing as far as possible the period .of contact with the alkaline precipitating solution, and by adding the carrier material containing silicate to the alkaline solution only when the precipitation of the catalytic metals has completely, or almost completely, ceased and the solution is no longerstrongly alkaline.

With special advantage carrier materials are employed Which have been rendered insoluble by dissolving out the soluble constituents. In some instances, the dissolving out of the soluble constituents may be preceded by heating these constituents to incandescence.

The catalysts precipitated on carrier materials used as carrier mass when as by occurring in nature. produced for example heat treatment of suitable salts such as the Insoluble oxides may be oxide by further heating the chromic oxide first obtained.

Insoluble oxides or silicates dissolving out from suitable substances occurring in nature or artificially produced, those are soluble in acid. By this means difilcultly soluble silicates such as steatite produce a suitable or ch'amotte can be treated to insoluble carrier material.

In certain cases it may be an advantage first to heat to incandescence the carrier material to be tive material.

It is therefore advisable even when using such carrier materials for the damage to the catalyst to place the carrier masses into the conby the decomposition by may be obtained version vessel only when the precipitation of the catalytically active metals has almost come to an end, so that the precipitating solution has no longer a strongly alkaline reaction.

In the same way as it is necessary to prevent any of the constituents of the carrier mass from dissolving during the precipitation of the catalytically active substances, care must be taken that on precipitation may afiect the catalyst. Foreign 7 substances may enter into solution during regeneration, as for example from the material of the vessel employed for carrying out this process (either by being mechanically removed or chemically dissolved), or from the chemicals employed during regeneration, such as the nitric acid employed for dissolving the catalysts that have become inactive. Moreover during the regeneration of the catalysts, constituents which were insoluble during the first production of the catalyst may pass into solution fromthe carrier mass under the possibly more severe conditions involved in the dissolving of the spentcatalysts. These noxious impurities are rendered ineffective by causing them to be removed from the solution containing the catalytic substances by a suitable precipitation.

It has been found advantageous to precipitate these noxious impurities by first adding a small quantity of the alkaline precipitating agent. After the removal of the first precipitate, for example by filtration, the actual metal catalysts are then precipitated by the further addition of the alkaline precipitating solution. In this case also it is advisable to add to the precipitating mixture the substances to be employed as carrier masses after the precipitation of the metal catalysts is completely or almost completely finished.

We claim: I

1. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a carrier catalyst which has ben obtained by pre-treatin the carrier material with acids to remove soluble constituents and combining, while avoiding a strongly alkaline reaction, the acid-treated carrier material with iron group metal compounds precipitated from salt solutions with alkaline pre- 3. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a catalyst deposited on natural carrier substances containing silicon dioxide, said catalyst having been obtained by pre-treating the carrier material with acids to remove soluble constituents, precipitating iron group metal compounds from salt solutions withalkaline precipitants and introducing the pre-treated carrier substance into the suspension or precipitate in the salt solution after the precipitati'on is completed so as to avoid a strongly alkaline reaction in the presence of said carrier substance; and separating normally liquid hydrocarbons from the reaction products 4. A process for the synthesis of normally liquid hydrocarbonsfrom a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a carrier catalyst which has beenobtainedby pro-treating the carrier-material with acids to remove'soluble constituents and combining, while avoiding a strongly alkaline reaction, the acid-treated carrier material'with iron group metal compounds precipitated from salt solutions with alkaline precipitants; separating normally liquid hydrocarbons from the reaction products; continuing the synthesis reaction until the activity of the catalyst is substantially reduced; treating the catalyst with acid to dissolve out the catalytically active constituents; removing from the acid solucipitants; and separating normally liquid hydroi carbons from the reaction products.

2. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a catalyst deposited on natural carrier substances containing silicon dioxide, said catalyst having been obtained by pretreating the carrier material with acids to remove soluble constituents, precipitating iron group metal compounds from salt solutions with alkaline precipitants and introducing the pre-treated carrier substance into the suspension of precipitate in the salt solution shortly before the precipitation is completed, so as to avoid a strongly alkaline reaction in the presence of said carrier substance; and separating normally liquid hydrocarbons from the reaction products.

tion by a preliminary precipitation with. a small amount of an alkaline precipitant the constituents dissolved out of the carrier material; precipitating the catalytically active constituents withalkaline precipitants and depositing said constituents upon the carrier material; washing and drying the catalyst thus obtained; and returning said catalyst to the synthesis reaction.

5. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a carrier catalyst which has been obtained by pre-treating the carrier material with acids to remove soluble constituents, preclpitatingiron group metal compounds from salt solutions with alkaline precipitants, and introducing the pre-treated carrier material into the suspension of precipitate in the salt solution after the precipitation is completed so as to avoid a strongly alkaline reaction in the presence of said carrier substance; separating normally liquid hydrocarbons from the reaction products; continuing the synthesis reaction until the activity of the catalyst is substantially reduced; treating the catalyst with acid to dissolve out the catalytically active constituents; removing from the acid solution by a preliminary precipitation with a small amount of an alkaline precipitant the constituents dissolved out of the carrier material; precipitating the catalytically active constituents with alkaline precipitants and depositing said constituents upon the carrier material; washing and drying the catalyst thus obtained; and returning said catalyst to the synthesis reaction.

6. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a carrier catalyst which has been obtained by heating the carrier material to incandescenc to make it less soluble, treating it thereafter with acids to remove soluble constituents and combining, while aseaaea 3 an alkaline precipitant the constituents dissolved avoiding a strongly alkaline reaction. the pretreated carrier material with iron group metal compounds precipitated from salt'solutions with alkaline precipitants; and separating normally liquid hydrocarbons from the reaction products.

7. A process for the synthesis of normally liquid hydrocarbons from a mixture of carbon monoxide and hydrogen, which comprises passing said mixture at a synthesis temperature over a carrier catalyst which has been obtained by pro-treating.

the carrier material with acids to remove soluble constituents, precipitating iron group metal compounds from salt solutions with alkaline precipitants, and introducing the pre-treated carrier material into the suspension of precipitate in the salt solution shortly before the precipitation is completed so as to avoid a strongly alkaline reaction in the presence of said carrier substance; separating normally liquid hydrocarbons from the reaction products; continuing the synthesis reaction until the activity of the catalyst is substantially reduced; treating the catalyst with acid to dissolve out the catalytically active constituents; removing from the acid solution by a preliminary precipitation with a small amount oi Q5 out of the carrier material; precipitating the catalytically active constituents with alkaline" precipitants and depositing said constituents upon the carrier material; washing and drying the catalyst thus obtained; and returning said catalyst to the synthesis reaction.

8. A process according to claim 4 wherein said catalytically active constituents are deposited upon the carrier material while avoiding a strongly alkaline reaction.

I 9. A process according to claim wherein said catalytically active constituents are deposited upon the carrier material shortly before the preo'r'ro ROELEN.

WALTER raiser; a 

